Internet service providers often employ a Layer 2 virtual private network (“L2VPN”) to provide private transport services from one customer site to another. A typical L2VPN uses multi-protocol label switching (“MPLS”) labels to route traffic between one provider edge (“PE”) device to another PE device. In order to meet service level agreements and to ensure that customer traffic is communicated properly, a provider often desires to monitor the traffic on a L2VPN. In some cases, it may be useful to monitor the traffic flow at one PE device from test equipment attached to the other PE device.
A common troubleshooting technique for monitoring such traffic is to monitor a port on one of the PE devices and send the transmitted and/or received traffic to a second port that is connected to a protocol analyzer or other test equipment. In the scenario where the port being monitored and the monitoring port are on the same router (or other device), or even when both edge devices are the same type of router, a standards-defined approach is not an issue, and vendor-proprietary monitoring techniques can be sufficient. However, in the scenario of a multi-vendor network, where the monitored port and port used for test equipment are on different devices there is no standard protocol or mechanism to provide for such monitoring. In such cases, there currently exists no known solution to allow remote monitoring of network traffic, especially in the case of a L2VPN, which is designed to prevent intermediate traffic inspection between the endpoints of the VPN. Hence, there is a need for more robust network monitoring solutions, and in particular solutions that can be used in the context of a L2VPN.